Modern vehicles incorporate various types of emission-reduction techniques within an exhaust system to reduce environmentally-harmful emissions. In some cases, exhaust systems are designed to reduce undesirable byproducts of combustion including nitrous oxide emissions from diesel engines. These exhaust systems may be highly sensitive to operating temperature of the exhaust system. For example, during cold starts of a diesel engine, the exhaust system including a selective catalytic reduction (SCR) system may be below an optimum temperature for proper treatment of exhaust gasses. It may take several minutes before the exhaust system reaches a steady-state operating temperature where emission reduction operates efficiently.
Several types of vehicle systems and strategies have been developed that rapidly heat up the exhaust system to reduce the time that the exhaust system runs at temperatures inefficient for exhaust gas treatment. However, these vehicle systems do not have built-in diagnostics that indicate whether rapid heat up is being properly performed. Therefore, a lack of reduction of harmful emissions may occur due to a lack of or delay in heating, which may not be noticed or remedied by a driver of the vehicle.